1. Field
Embodiments of the present invention are generally directed to electrical device fabrication, and more particularly to, the formation of electrically insulating elements and electrically conductive elements from elements having different oxidation behaviors which are subjected to an oxidation process.
2. Description of Related Art
Plated metal processes are heavily used in micro-electrical-mechanical system (MEMS) power and radio frequency (RF) components due to their low resistances and correspondingly low power losses. For large free-standing devices, mechanical supports are often necessary to improve robustness and to prevent deflection and shorting with neighboring structures. Since electroplated metals are conductive, creating resistive or dielectric supports has traditionally been done by the deposition and patterning of additional dielectric materials such as polymers or plastics. An alternative means of creating a resistive or dielectric support is to convert an electrically conductive element to a more resistive material by an oxidation process. The oxidation of silicon to silicon oxide to create dielectric mechanical supports has been previously demonstrated in microstructure fabrication. For some applications, a trench may be filled with silicon oxide through thermal oxidation and used to form the mechanical anchor of a micromechanical structure. Alternatively, silicon beams and mechanical supports can be directly converted to silicon oxide to form dielectric mechanical supports. Other prior work has also demonstrated the use of oxidation of silicon to create silicon oxide mechanical structures such as membranes. Although many metals also form thick oxides, this has typically been viewed as a major problem, especially in MEMS packaging where exposure to temperatures of several hundred degrees Celsius may be required, and has not been previously relied upon to create mechanical structures.